Evaluate the following expression when $a = 4$ and $b = 3$. $3$ $a$ $ + 6$ $b$ $ - 10$
Answer: Substitute $4$ for ${a}$ and $3$ for ${b}$ $ = 3{(4)} + 6{(3)} - 10 $ $ = 12 + 18 - 10 $ $ = 20$